Biodegradable Interpolyelectrolyte Complexes Based on Methoxy Poly(ethylene glycol)-b-poly(alpha,L-glutamic acid) and Chitosan

We synthesized methoxy poly(ethylene glycol)-b-poly(alpha,L-glutamic acid) (mPEGGA) diblock copolymer by ring-opening polymerization of N-carboxy anhydride of gamma-benzyl-L-glutamate (NCA) using amino-terminated methoxy polyethylene glycol (mPEG) as macroinitiator. Polyelectrolyte complexation between mPEGGA as neutral-block-polyanion and chitosan (CS) as polycation has been scrutinized in aqueous solution as well as in the solid state.

Extracellular carbohydrate polymers from five desert soil algae with different cohesion in the stabilization of fine sand grain

Extracellular polymeric substances (EPS) from four filamentous cyanobacteria Microcoleus vaginatus, Scytonema javanicum, Phormidium tenue and Nostoc sp. and a coccoid single-cell green alga Desmococcus olivaceus that had been separated from desert algal crusts of Tegger desert of China, were investigated for their chemical composition, structure,and physical properties. The EPS contained 7.5-50.3% protein (in polymers ranging from 14 to more than 200 kD, SDS-PAGE) and 16.2-46.5% carbohydrate (110-460 kD, GFC). 6-12 kinds of monosaccharides, including 2-O-methyl rhamnose, 2-O-methyl glucose, and N-acetyl glucosamine were found. The main carbohydrate chains from M. vaginatus and S. javanicum consisted mainly of equal proportion of Man, Gal and Glc, that from P. tenue consisted mainly of arabinose, glucose and rhamnose. Arabinose was present in pyranose form, mainly alpha-L 1 --> 3 linked, with branches on C4 of almost half of the units. Glucose was responsible for the terminal units, in addition of having some units as beta1 --> 3 and some as beta1 --> 4 linked. Rhamnose was mainly 1 --> 3 linked with branches on C2 on half of the units. The carbohydrate polymer from D. olivaceus was composed mainly of beta1 --> 4 linked xylose, galactose and glucose. The galactose part was present both in beta-pyranose and -furanose forms. Arabinose in alpha-L-furanose form was mainly present as 1 --> 2 and 1 --> 2, 5 linked units, rhamnose only as alpha 1 --> 3 and xylose as beta 1 --> 4. The backbone of the polysaccharide from Nostoc sp. was composed of beta-1 --> 4 linked xylose, galactose and glucose. Most of the glucose was branched on position C6, terminal glucose and 2-O-methyl glucose units are also present. The relationship between structure, physical properties and potential biological function is discussed. (C) 2003 Elsevier Ltd. All rights reserved.

Structure identification of a prenylflavonol glycoside from Epimedium koreanum by electrospray ionization tandem mass spectrometry

A novel prenylflavonol glycoside, named acetylicariin, has been isolated from the aerial parts of Epimedium koreanum Nakai. The structure has been identified by electrospray ionization multi-stage tandem mass spectrometry (ESI-MSn) and other chemical evidence, which has been elucidated as 8-prenylkaempferol-4'-methoxyl-3-O-alpha-L-rhamnopyranosyl-7-O-beta-D-(2''-O-acetyl)glucopyranoside.

Identification of the flavonoid constituents from leaves of Acanthopanax Senticosus Harms

Four flavonoids from leaves of Acanthopanax Senticosus Harms were observed in negative ion mode in the electrospray mass spectra. Two of them were further isolated and identified as quercitrin (quercetin-3-O-alpha-L-rhamnoside) and hyperin (quercetin-3-O-beta-D-galactoside) on the basis of MS' and NMR data. The other two compounds in the mixtures were tentatively established as quercetin and rutin (quercetin-3-O-rutinoside) in terms of their electrospray tandem mass spectrometry (ESI-MSn) data. Three of the four flavonoids (excluding hyperin) haven't been reported in this plant before.

An acidic polysaccharide with xylose branches from Porphyra yezoensis

An acidic polysaccharide (PY3) was isolated from the hot water extract of the red algae Porphyra yezoensis by successive column chromatographies over DEAE-cellulose and Sephadex G-200. PY3 with an average molecular weight of 1.8x10(5) was demonstrated to be composed of galactose (Gal), 3,6-anhydrogalactose (3,6-AnGal), 6-OSO3-galactose (6-OSO3-Gal) and xylose (Xyl) in an approximate molar ratio of 25 : 15, 10, 1. In view of Smith degradation and methylation and on the basis of spectral evidence including those of IR, GC, GC-MS, and H-1 and C-13 NMR, the most probable repeating unit of PY3 could be proposed as [(1-->3)beta -D-Gal(1 --> 4)alpha -L-3,6-AnGal](3)-[(1 --> 3)beta -D-Gal(1 --> 4)alpha -L-6-OSO3-Gal](2) with a xylose moiety at the C-6 of one of every twenty-five beta -D-Gal residues. To our knowledge, PY3 was shown to be the first porphyran possessing occasional xylose branches.

Chemical characteristics of a polysaccharide from Porphyra capensis (Rhodophyta)

The structure of a polysaccharide from the red seaweed, Porphyra capensis, growing along the coast of Namibia and South Africa was investigated. Algae growing at different sites and collected at different times gave a polysaccharide extract with similar chemical components. FTIR and NMR spectral analysis showed that the polysaccharide from P. capensis had a typical porphyran structure. It has the linear backbone of alternating 3-linked beta-D-galactose and 4-linked alpha-L-galactose-6-sulfate or 3,6-anhydro-alpha- L-galactose units. The ratio of alpha-L-galactose-6-sulfate and the 3,6-anhydrogalactose is 121, as reflected by a H-1 NMR spectrum. A high degree of methylation occurred at the C-6 position of the D-galactose units. The degree of methylation was 0.64 for the D-galactose residues. (C) 2005 Elsevier Ltd. All rights reserved.

The structure of a sulfated galactan from Porphyra haitanensis and its in vivo antioxidant activity

The sulfated galactan fraction F1 isolated from the red seaweed, Porphyra haitanensis, showed typical porphyran structure. It has a linear backbone of alternating 3-linked beta-D-galactosyl units and 4-linked alpha-L-galactosyl 6-sulfate and 3,6-anhydro-alpha-L-galactosyl units. The L-residues are mainly composed of alpha-L-galactosyl 6-sulfate units, and the 3,6-anhydrogalactosyl units are minor. Partial methylation occurred at the C-6 position of the D-galactosyl units and at the C-2 position of the 3,6-anhydro-alpha-L-galactosyl units. Intraperitoneal administration of F1 significantly decreased the lipid peroxidation in aging mice. F1 treatment increased the total antioxidant capacity and the activity of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) in aging mice. The results indicated that F1 had significant in vivo antioxidant activity. (C) 2003 Elsevier Ltd. All rights reserved.

Polysaccharides from Ulva pertusa (Chlorophyta) and preliminary studies on their antihyperlipidemia activity

Polysaccharides from Ulva pertusa were isolated and prepared by extraction in hot water and precipitation by ethanol. The water-soluble polysaccharides were chemically well defined, containing 47.0% total carbohydrate, 23.2% uronic acids, 17.1% sulfate groups, 1.0% N and 29.9% ash. Gas chromatography analysis demonstrated that the neutral sugars were mainly composed of rhamnose, xylose and glucose and smaller amounts of mannose, galactose and arabinose. The FTIR and C-13-NMR spectra indicated that basic repeating units of the polysaccharides were (beta-D-GlcpA-(1->4)-alpha-L-Rhap 3S) and (alpha-L-IdopA-(1->4)-alpha-L-Rhap 3S). Fifty ICR mice were used to study the effect of water-soluble polysaccharides from Ulva pertusa on the level of plasma lipids, with inositol niacinate as positive control. The results indicated that the polysaccharides significantly lowered the contents of plasma total cholesterol, low-density lipoprotein cholesterol, triglyceride and markedly increased the contents of serum high-density lipoprotein cholesterol, compared with the hyperlipidemia control group (p<0.01). Moreover, administration of polysaccharides significantly decreased the atherogenic index. The present results suggest that the polysaccharides from Ulva pertusa have great potential for preventing ischemic cardiovascular and cerebrovascular diseases.

Structural studies on a novel fucogalactan sulfate extracted from the brown seaweed Laminaria japonica

A low molecular weight fucogalactan, obtained from the brown seaweed Laminaria japonica, was separated into three fractions (LF1, LF2 and LF3) by DEAE-Sepharose FF column chromatography. All three fractions contained predominantly fucose, sulfate group and galactose. The results showed that the main fraction LF2 consisted of L-fucose, D-galactose and sulfate at a molar ratio 6:1:9. Structural study on the LF2 was carried out by NMR spectroscopy. The backbone of LF2 was primarily (1 -> 3)-linked alpha-L-fucopyranose residues (75%) and a few (1 -> 4)-alpha-L-fucopyranose linkages (25%). The branch points were at C-4 of 3-linked alpha-L-fucopyranose residues by beta-D-galactopyranose unites (35%, molar ratio) or at C-2 of 3-linked alpha-L-fucopyranose residues by non-reducing terminal fucose unites (65%, molar ratio). Sulfate groups occupied at position C-4 or C-2, sometimes C-2, 4 to fucose residues, and C-3 and/or C-4 to galactose residues. The structure of LF2 was supposed as following: [GRAPHICS] (C) 2010 Elsevier B.V. All rights reserved.

Separation and determination of flavone and xanthone glycosides in Tibetan folk medicinal species Swertia mussotii and S-franchetiana by capillary electrophoresis

The contents of five pharmacologically active flavone and xanthone glycosides, namely, swertianolin, swertisin, isoorientin, mangiferin, and 7-O-[alpha-L-rhamnopyranosyl-(1 -> 2)-beta-D-xylopyranosyl]-1,8-dihydroxy-3-methoxyxanthone, extracted from Tibetan folk medicinal species Swertia mussotii and S. franchetiana were determined by capillary electrophoresis with diode-array detection. The separation of five components has been optimized with a capillary column with a total length of 48.5 cm and effective length of 40 cm (50 mu m i.d). The influence of the running buffer, the sodium dodecyl sulfonate (SDS) concentration, organic modifier, etc. on the resolution was evaluated. The background electrolyte contained 30 mM borate buffer, 28 mM SDS, 1.0% (v/v) acetonitrile, and was adjusted to pH 9.0 with 0.1 M NaOH. A good baseline resolution was obtained for the separation of five components within 5 min with the working voltage of 24 kV and a column temperature of 25 degrees C. The established method was rapid and reproducible for the separation and determination of five flavone and xanthone glycosides from the extracts of S. mussotii and franchetiana plant samples.

Two new benzochromone glycosides from the stem of Berchemia racemosa

Two new benzochromone glycosides, rubrofusarin 6-O-alpha-L-rhamnosyl- (1 -> 6)-O-beta-D-glucopyranoside (1) and demethylflavasperone 10-O-beta-D-glucopyranoside (2), have been isolated from the stem of Berchemia racemosa Sieb. et Zucc. (Rhamnaceae). Their structures were elucidated on the basis of spectroscopic evidence.

Separation and determination of the major active components in Tibetan folk medicinal species Swertia franchetiana by HPLC with DAD

A sensitive and specific reversed-phase high performance liquid chromatography (RP-HPLC) method with diode array detection (DAD) was established for the quantitative determination of the nine active components, namely, swertiamarin (SWM, 1), mangiferin (MA, 2), gentipicroside (GE, 3), sweroside (SWO, 4), isoorientin (IS, 5), swertisin (SWS, 6), swertianolin (SWN, 7), 7-O-[alpha-L-rhamnopyranosyl-1 -> 2)-beta-D-xylopyranosyl]-1,8-dihydroxy-3-methoxyxanthone (RX, 8), and bellidifolin (BE, 9) used as the external standard, in Tibetan folk medicinal species Swertia franchetiana. Based on the baseline chromatographic separation of most components from the methanolic extract of Swertia franchetiana on a reversed-phase Eclipse XDB-C8 column with water-acetonitrile-formic acid as mobile phase, the nine components were identified by comparison with standard samples and qualified by using the external standard method with DAD at 254 nm. The correlation coefficients of all the calibration curves were found to be higher than 0.9980. The relative standard deviations (RSDs) of the peak areas and retention times for the nine standards were less than 2.07% and 2.86%, respectively.

Angular distribution and conversion of multi-keV L-shell X-ray sources produced from nanosecond laser irradiated thick-foil targets

An experimental study on the angular distribution and conversion of multi-keV X-ray sources produced from 2 ns-duration 527nm laser irradiated thick-foil targets on Shenguang II laser facility (SG-II) is reported. The angular distributions measured in front of the targets can be fitted with the function of f(theta) = alpha+ (1- alpha)cos(beta) theta (theta is the viewing angle relative to the target normal), where alpha = 0.41 +/- 0.014, beta = 0.77 +/- 0.04 for Ti K-shell X-ray Sources (similar to 4.75 keV for Ti K-shell), and alpha = 0.085 +/- 0.06, beta = 0.59 +/- 0.07 for Ag/Pd/Mo L-shell X-ray Sources (2-2.8 keV for Mo L-shell, 2.8-3.5 keV for Pd L-shell, and 3-3.8 keV for Ag L-shell). The isotropy of the angular-distribution of L-shell emission is worse than that of the K-shell emission at larger viewing angle (>70 degrees), due to its larger optical depth (stronger self-absorption) in the cold plasma side lobe Surrounding the central emission region, and in the central hot plasma region (emission region). There is no observable difference in the angular distributions of the L-shell X-ray emission among Ag, Pd, and Mo. The conversion efficiency of Ag/Pd/Mo L-shell X-ray sources is higher than that of the Ti K-shell X-ray sources, but the gain relative to the K-shell emission is not as high as that by using short pulse lasers. The conversion efficiency of the L-shell X-ray sources decrease, with increasing atomic numbers (or X-ray photon energy), similar to the behavior of the K-shell X-ray Source.

Fabrication of beta-BaB2O4 layers on (001) Sr2+-doped alpha-BaB2O4 by vapor transport equilibration (VTE)

Crystalline beta-BBO layers have been successfully prepared on (0 0 1)-oriented Sr2+-doped alpha-BBO substrates using vapor transport equilibration technique. The layers were characterized by X-ray diffraction, X-ray rocking curve and transmission spectra. The present results manifest that the VTE treatment time and powder ratio are important factors on the preparation of beta-BBO layers. beta-BBO layers with a highly (0 0 l) preferred orientation were obtained according to XRD profiles. The full width at half-maximum of the rocking curve for the layer is as low as about 1000 in., which shows the high crystallinity of the layer. These results reveal the possibility of fabricating beta-BBO (0 0 1) layers on (0 0 1)-oriented Sr2+-doped alpha-BBO substrates by VTE. (C) 2006 Elsevier Ltd. All rights reserved.

Polymorphisms of the estrogen receptor alpha (ESR1) gene and the risk of Alzheimer's disease in a southern Chinese community

Background: Alzheimer's disease (AD) is a neurodegenerative disease with a higher prevalence in women. Expression of estrogen receptor 1 (ESR1) gene has been identified throughout the brain. Owing to the putative neuroprotective effects of estrogen, estro